// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// SHA256 block step.
// In its own file so that a faster assembly or C version
// can be substituted easily.

// package sha256 -- go2cs converted at 2022 March 13 05:34:25 UTC
// import "crypto/sha256" ==> using sha256 = go.crypto.sha256_package
// Original source: C:\Program Files\Go\src\crypto\sha256\sha256block.go
namespace go.crypto;

using bits = math.bits_package;

public static partial class sha256_package {

private static uint _K = new slice<uint>(new uint[] { 0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070, 0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2 });

private static void blockGeneric(ptr<digest> _addr_dig, slice<byte> p) {
    ref digest dig = ref _addr_dig.val;

    array<uint> w = new array<uint>(64);
    var h0 = dig.h[0];
    var h1 = dig.h[1];
    var h2 = dig.h[2];
    var h3 = dig.h[3];
    var h4 = dig.h[4];
    var h5 = dig.h[5];
    var h6 = dig.h[6];
    var h7 = dig.h[7];
    while (len(p) >= chunk) { 
        // Can interlace the computation of w with the
        // rounds below if needed for speed.
        {
            nint i__prev2 = i;

            for (nint i = 0; i < 16; i++) {
                var j = i * 4;
                w[i] = uint32(p[j]) << 24 | uint32(p[j + 1]) << 16 | uint32(p[j + 2]) << 8 | uint32(p[j + 3]);
            }


            i = i__prev2;
        }
        {
            nint i__prev2 = i;

            for (i = 16; i < 64; i++) {
                var v1 = w[i - 2];
                var t1 = (bits.RotateLeft32(v1, -17)) ^ (bits.RotateLeft32(v1, -19)) ^ (v1 >> 10);
                var v2 = w[i - 15];
                var t2 = (bits.RotateLeft32(v2, -7)) ^ (bits.RotateLeft32(v2, -18)) ^ (v2 >> 3);
                w[i] = t1 + w[i - 7] + t2 + w[i - 16];
            }


            i = i__prev2;
        }

        var a = h0;
        var b = h1;
        var c = h2;
        var d = h3;
        var e = h4;
        var f = h5;
        var g = h6;
        var h = h7;

        {
            nint i__prev2 = i;

            for (i = 0; i < 64; i++) {
                t1 = h + ((bits.RotateLeft32(e, -6)) ^ (bits.RotateLeft32(e, -11)) ^ (bits.RotateLeft32(e, -25))) + ((e & f) ^ (~e & g)) + _K[i] + w[i];

                t2 = ((bits.RotateLeft32(a, -2)) ^ (bits.RotateLeft32(a, -13)) ^ (bits.RotateLeft32(a, -22))) + ((a & b) ^ (a & c) ^ (b & c));

                h = g;
                g = f;
                f = e;
                e = d + t1;
                d = c;
                c = b;
                b = a;
                a = t1 + t2;
            }


            i = i__prev2;
        }

        h0 += a;
        h1 += b;
        h2 += c;
        h3 += d;
        h4 += e;
        h5 += f;
        h6 += g;
        h7 += h;

        p = p[(int)chunk..];
    }

    (dig.h[0], dig.h[1], dig.h[2], dig.h[3], dig.h[4], dig.h[5], dig.h[6], dig.h[7]) = (h0, h1, h2, h3, h4, h5, h6, h7);
}

} // end sha256_package
